Socceroos walking a tightrope on road to Russia

"IT'S the biggest game of the last two years of qualifying. Just huge. People actually don't realise this is a massive game in Australian football."

Not for the first time this season, Jamie Maclaren has hit the target - if not this time with the ball, then with his words.

In fact, if anything, he's slightly understated the importance of Australia's clash with Saudi Arabia on Thursday night.

It surely has to be the most crucial match since the Asian Cup final of January 2015.

Ange Postecoglou doesn't particularly want that label - it can bring its own pressures for one thing - preferring to insist that "all games are big" at this stage of qualifying.

He's right, but such is the precarious state of the Socceroos' quest to reach Russia that a loss - however unthinkable that might be - coupled with a win for Japan over Iraq on the same night, would leave the Roos six points off the top two with just two matches to play.

Effectively, they would then be ruled out of the automatic qualification spots, particularly as both Japan (currently in first place in Group B) and the Saudis (second), have superior goal differences.

With fourth-placed UAE facing bottom-placed Thailand on the same night, success for the Emiratis could leave the Aussies just one point ahead of them and facing a real fight to even hold on to a playoff spot. All that with Japan to come next - in Saitama.

Even if third was to be the outcome, there would still be no guarantees. Australia would then have to face the equivalent team from the other group (currently Uzbekistan), and then the fourth-placed CONCACAF team, which, as things stand, is - intriguingly - the United States.

That's all worst-case scenario stuff of course.

The flip side of the equation is a win by a two-goal margin will elevate the Roos back into a top-two spot and leave their destiny very much in their own hands. It's also worth remembering Saudi Arabia has only beaten the Australians once in seven previous meetings, and that Australia remains the only undefeated team in the section.

Yet those four consecutive draws have left little margin for error in Adelaide, against an opponent which showed new-found resilience in snatching a late equaliser in the return fixture in Jeddah after Australia had taken a 2-1 lead with less than 20 minutes to go.

The Saudis, aiming for a first World Cup finals since 2006, have always had players with good technical ability, but coach Bert Van Marwijk has added steel, just as he did with his native Netherlands, leading it to the 2010 World Cup final.

He's had plenty of preparation for this game too, with a lengthy camp in Frankfurt ahead of the trip to Australia.

He's also shown he's not afraid to make big decisions concerning star players.

Last October, Van Marwijk recalled the controversial Nasser Al-Shamrani for the game against Australia, who rewarded that faith by scoring the late equaliser in Jeddah.

This time he has omitted golden boy Naif Hazazi from the squad due to fitness concerns - and perhaps also because the player has had a bit of a fallout with his club side, Al-Nasr.

Van Marwijk will also have to do without the injured Hassan Muath and Fahad Al-Muwalad, and the suspended Nawaf Al-Abed, for the trip - a quartet, including Hazazi, who all played a part in the draw in Jeddah.

That means either Al-Shamrani or, more likely, Mohammed Al-Sahlawi will lead the attack, and the rumour in the Saudi press is that Van Marwijk will respond to Postecoglou's new playing system by packing the midfield - perhaps to play for a point.

Salem Al-Dawsari could be the beneficiary, having earned a first call-up in more than a year. You may remember him scoring a screamer against Australia in Melbourne in 2012.

Postecoglou's 3-2-4-1 has been called into question in Australia, as much for its timing as anything else. But the Socceroos coach isn't about to change tack, and believes his decisions wouldn't be up for debate if he were a foreign coach - although Pim Verbeek and Holger Osieck might tell him differently.

Postecoglou has already confirmed he'll be moving on at the end of Australia's World Cup campaign, which only adds further emphasis to Thursday night's encounter. Ange will want to cement his legacy as the most successful national team coach of all-time - and any failure to qualify for the World Cup would leave a nasty stain on his record.

In all likelihood, it would probably mean a premature parting of the ways.

You can also guarantee that with an estimated $20 million the reward for those nations who reach the big dance, a financially strapped FFA is sweating heavily on the outcome too.